1. Technical Field
This invention relates to vehicle suspension systems for mounting ground-engaging wheels to a vehicle frame, and, more particularly, to a trailing arm suspension axle support means for securing a wheel-carrying axle to a vehicle.
2. Description of Related Art
In U.S. Pat. No. 4,693,486 to Pierce, et al. (issued Sept. 15, 1987) a trailing arm suspension has an axle secured to a trailing arm by a wrapper plate partially surrounding the axle, a bolt is utilized to compress the wrapper plate about the axle so that the wrapper plate supports and strengthens the axle, and a circular plug weld attaches the wrapper plate to the axle.
The U.S. Pat. No. 3,547,215 to Bird (issued Dec. 15, 1970) discloses a trailing arm suspension wherein a square axle is typically welded to a bracket which is, in turn, secured to the trailing arm of the vehicle suspension structure. The weldment securing the axle to the bracket is usually made at the mid-point of the side of the axle where vertical bending moment stresses are neutral. However, these areas are areas of high torsional loading which results from brake torque, vehicle roll and diagonal axle (wheel) walk. The welding at the mid-point of the axle may introduce a point of weakness where cracks can initiate. The weakness in the typical axle welded to a bracket is caused, in part, by the undesirable heat-treating effects of the welding process upon the axle material in the localized area adjacent to the weldment. In addition, craters or strike marks may form points at which cracks may initiate or at which stresses may become concentrated.
Axles are typically welded to the brackets in order to securely attach the axle to the bracket under this high loading condition. The axle is welded to the axle bracket by a line weld on either side of the bracket. Because it is a line weld, the weldment has "ends" at which stresses are concentrated and at which cracks may initiate.
The trailing arm suspension system, according to the invention, overcomes the cracking problems of the weld between the axle and the bracket described above in the prior art. The wrapper plate of the suspension system of the invention is fixedly attached to the axle through mechanical means without welding of the axle. This mechanical attachment results in an axle support assembly which is easily fixedly attached to the axle and avoids the above-described failures between the axle and bracket.